The Nutritional Epidemiology Shared Resource provides comprehensive nutritional science support to Cancer Prevention Research Programs involving nutrition intervention, nutrient supplementation, and dietary assessment. Members of the shared resource include three doctoral level epidemiologists also trained in nutritional science and a clinical nutritionist experienced in research-oriented nutrition intervention and dietary assessment techniques. Specific activities of the shared resource are to: (1) Develop and validate instruments for dietary assessment; (2) Provide analytic support for the interpretation of diet and nutrition-related biochemical measures; (3) Investigate potential biochemical markers of dietary intake or intervention compliance; and (4) Maintain structured surveillance of the nutrition literature on the safety of nutritional supplements and dietary modifications under investigation as cancer control interventions. Members of the Nutritional Epidemiology Shared Resource also pursue methodological research focused toward improving cancer control nutrition intervention research.